Joint or segmental bone implant for deformity correction

ABSTRACT

An implant is provided for use in an ankle joint between reconditioned end surfaces established on a distal end of an upper tibia bone and an opposing lower talus bone. The implant comprises a substantially porous rigid component adapted to be anchored against the upper tibia reconditioned end surface and the lower talus reconditioned end surface. The component defining an opening therethrough. An intramedullary nail is configured to pass through the opening in the component when the nail is driven through the talus and into the tibia.

CROSS-REFERENCE

This application is related to U.S. provisional application No.62/165,376, filed May 22, 2015, entitled “JOINT OR SEGMENTAL BONEIMPLANT FOR DEFORMITY CORRECTION”, naming Samuel Adams as the inventor.The contents of the provisional application are incorporated herein byreference in their entirety, and the benefit of the filing date of theprovisional application is hereby claimed for all purposes that arelegally served by such claim for the benefit of the filing date.

BACKGROUND

A medical implant is described and, more particularly, a medical implantfor use in joint or segmental bone defects for deformity correction withor without obtaining arthrodesis.

Implants may be used in humans or animals to support or secure one ormore bones. Once implanted, the implant may provide support between thebones and bone growth may take place around and through the implant toat least partially fuse the bones for long-term support.

There is a need for an improved medical implant for use in body areas,such as bones of the foot and ankle.

SUMMARY

An implant is provided for use in an ankle joint between reconditionedend surfaces established on a distal end of an upper tibia bone and anopposing lower talus bone. The implant comprises a substantially porousrigid component adapted to be anchored against the upper tibiareconditioned end surface and the lower talus reconditioned end surface.The component defining an opening therethrough. An intramedullary nailis configured to pass through the opening in the component when the nailis driven through the talus and into the tibia.

A method of securing an ankle joint is also provided. The methodcomprises the steps of reconditioning end surfaces on a distal end of anupper tibia bone and an opposing lower talus bone of the ankle joint. Asubstantially porous rigid component is positioned against the uppertibia reconditioned end surface and the lower talus reconditioned endsurface. The component defining an opening therethrough. Anintramedullary nail configured to be driven through the through thetalus and the opening in the component and into the tibia.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the bone implant, reference shouldnow be had to the embodiments shown in the accompanying drawings anddescribed below. In the drawings:

FIG. 1 is a top plan view of an embodiment of a joint or segmental boneimplant.

FIG. 2 is a top perspective view of the bone implant as shown in FIG. 1.

FIG. 3 is a perspective view of the bone implant as shown in FIG. 1receiving a portion of an intramedullary nail.

FIG. 4 is a perspective view of the bone implant as shown in FIG. 1positioned in a foot and ankle joint.

FIG. 5 is an exploded perspective view of the bone implant and the footand ankle joint as shown in FIG. 4.

FIG. 6A is a side elevation view of the bone implant as shown in FIG. 1positioned in a foot and ankle joint.

FIG. 6B is an opposite side elevation view of the bone implantpositioned in a foot and ankle joint as shown in FIG. 6A.

FIG. 6C is a rear perspective view of the bone implant positioned in afoot and ankle joint as shown in FIG. 6A.

FIG. 6D is a front perspective view of the bone implant shown in phantompositioned in a foot and ankle joint as shown in FIG. 6A.

FIG. 6E is a top perspective view of the bone implant positioned in afoot and ankle joint as shown in FIG. 6A.

FIG. 7A is a side elevation view of the bone implant as shown in FIG. 1positioned in a foot and ankle joint and a portion of an intramedullarynail shown in phantom.

FIG. 7B is a rear perspective view of the bone implant positioned in afoot and ankle joint as shown in FIG. 7A.

FIG. 7C is an opposite side elevation view of the bone implantpositioned in a foot and ankle joint as shown in FIG. 7A.

FIG. 7D is a top plan view of the bone implant positioned in a foot andankle joint as shown in FIG. 7A.

FIG. 7E is an up-close view of the bone implant positioned in a foot andankle joint as shown in FIG. 7A.

FIG. 8 is a perspective view of another embodiment of a bone implantpositioned in a foot and ankle joint and including a fixation device.

FIG. 9 is an elevation view of a third embodiment of a bone implanthaving a planar surface to accommodate a plate or other device.

FIG. 10 is an elevation view of a fourth embodiment of a bone implantpositioned in a foot and ankle joint.

FIG. 11 is a perspective view of fifth embodiment of a bone implant foruse in a foot and ankle joint.

FIG. 12 is a perspective view of a sixth embodiment of a bone implantfor use in a foot and ankle joint.

FIG. 13 is schematic elevation view of the third embodiment of the boneimplant as shown in FIG. 9 between two portions of bone.

FIG. 14 is schematic elevation view of a seventh embodiment of a boneimplant shown between two portions of bone.

DESCRIPTION

Certain terminology is used herein for convenience only and is not to betaken as a limitation on the invention. For example, words such as“upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,”and “downward” merely describe the configuration shown in the FIGS.Indeed, the components may be oriented in any direction and theterminology, therefore, should be understood as encompassing suchvariations unless specified otherwise.

Referring now to FIGS. 1 and 2, there is shown an embodiment of amedical joint or segmental bone implant for deformity correction andgenerally designated at 20. The implant 20 comprises a porous webstructure 22 configured to interface with human bone tissue. The webstructure 22 extends throughout the implant 20 to provide support. Theweb structure 22 disperses the stress of compressive forces throughoutimplant 20, wherein the implant 20 is supported against tensile,compressive, and shear forces. The web structure 22 can be furtheremployed to receive and distribute throughout the implant 20 loadingforces of the surrounding tissue. The web structure 22 may alsoreinforce the implant 20 along multiple planes.

In one embodiment, the web structure 22 is formed with interconnectedtriangular-shaped building blocks. The result is a web structure 22formed from a pattern of triangularly-shaped geometrical buildingblocks. The triangularly-shaped building blocks may form tetrahedronsthat may also be used as building blocks. Other patterns from thetriangles are also contemplated. Each tetrahedron may include fourtriangular faces in which three of the four triangles meet at eachvertex. At least two of the plurality of tetrahedrons are coupledtogether via one or more common components connecting two respectivevertices on each of the two tetrahedrons such that two tetrahedronsshare a common unit to form a hexahedron.

In one embodiment, the porous web structure 22 is configured to form asubstantially spherical structure as shown in FIGS. 1 and 2. The implant20 can have a diameter of at least about 38 mm to about 40 mm. However,it is understood that the design of the implant 20 may be sizedappropriately to meet specified dimensions of the implantation site. Insome embodiments, multiple implants of different sizes may beconstructed and delivered in a kit. A medical health professional maychoose an implant (e.g., according to a needed size) during surgery. Itis understood that while the embodiment of the implant 20 has beendescribed with respect to a particular spherically-shaped web structure,various shapes of web structures are contemplated. For example, aportion of the spherical implant may be removed to form an implant 44having a planar side (FIGS. 9 and 14). In another embodiment shown inFIG. 13, the implant 54 may be egg-shaped (FIG. 13).

The implant 20 may be formed from a biocompatible material such as atitanium alloy (e.g., y-titanium aluminides), cobalt, chromium,stainless steel, polyetheretherketone (PEEK), ceramics, or othersuitable material. The implant 20 may be made through a rapidprototyping process (e.g., electron beam melting (EBM) process). Otherprocesses are also possible, such as injection molding, casting,sintering, selective laser sintering (SLS), direct metal laser sintering(DMLS), etc). SLS may include laser-sintering of high-performancepolymers such as that provided by EOS of North America, Inc.,headquartered in Novi, Mich., U.S.A. High-performance polymers mayinclude various forms of PEEK (e.g., HP3 having a tensile strength of upto about 95 mega Pascal (MPa) and a Young's modulus of up to about 4400MPa and continuous operating temperature between about 180° C. (356° F.)and 260° C. (500° F.)). Other materials may include PA 12 and PA 11provided by EOS of North America, Inc. Multiple parts may be cast orinjection molded and joined together (e.g., through welding, melting,etc.). For example, individual components 24 forming the implant 20 maybe generated separately (e.g., by casting, injection molding, etc.) andwelded together to form the implant 20. The porous web structure 22 maybe made according to the disclosure of International Application No.PCT/US2012/045717, filed Jul. 6, 2012, and published Jan. 10, 2013, asInternational Publication No. WO 2013/006778, the contents of which arehereby incorporated by reference in their entirety.

In another embodiment shown in FIG. 12 and generally designated at 50,the web structure 22 of the implant 50 may be formed from a generallyporous material having random openings 45.

The implant 20, 50 may include a top face 26 and an opposed bottom face28 wherein at least a portion of the top face 26 and the bottom face 28are generally parallel to one another. In use, the top and bottom faces26, 28 are configured to be disposed in contact, or near contact, of anadjacent bony structure for contacting the bony structure during use toadhere or couple with the adjacent structure when implanted. Asdepicted, for example, the implant 20, 50 is intended to sandwichbetween two adjacent bony structures interfacing with bone structure ofa foot and ankle joint 34. The top contact face 26 may couple to aportion of the first bony structure disposed above implant 20 and thebottom contact face 28 may couple to the second bony structure disposedbelow implant 20.

The web structure 22 defines openings configured to define open volumeto enable bone growth through the openings of the web structure 22,thereby enhancing coupling of the implant 20 to the adjacent bonystructure. At least a portion of the web structure 22 is in contact, ornear contact, with the adjacent bony structure, thereby enabling bonegrowth to extend into or through at least a portion of open volume ofthe web structure 22 such that the bone growth interlocks with the webstructure 22 of the implant 20. The interlocking of the bone growth andthe web structure 22 may rigidly fix the implant 20 in a fixed locationrelative to the bony structure. For example, a web structure 22 maydefine an open space for bone growth therethrough, thereby enabling bonethrough growth to interlock the bone structure and the web structure 22with one another to couple the implant 20 to the bony structure at ornear the contact surface. Such interlocking bone through growth mayinhibit movement between the implant 20 and the bony structure, whichcould otherwise lead to loosening, migration, subsidence, or dislodgingof the implant 20 from the intended position.

The web structure 22 of the implant 20 may also provide surface area forbone graft fusion. For example, the voids in the web structure 22 of theimplant 20 may be filled with, or surfaces of the web structure 22 maybe coated with, bone grafting material, a biologic, growth factor or thelike. The web structure 22 extending throughout the implant 20 may addadditional surface area on the surface of the components 24 to fuse tothe bone graft material and prevent the bone graft material fromloosening or migrating from the implant 20. In some embodiments, the webstructure 22 may also support and facilitate bone in-growth. Forexample, adjacent bone in an ankle joint may grow over at least aportion of the components 24 of the implant 22. The bone growth andengagement between the bone growth and the implant 20 may furtherstabilize the implant. In some embodiments, the surfaces of the implant20 may be formed with a rough surface to assist in bone in-growthadhesion.

At least a portion of the open volume of the web structure 22 of theimplant 20 may be filled with bone growth material. For example,cancellous bone may be packed into the openings internally of theimplant 20. In some embodiments, at least a portion of the surfaces ofimplant 20 may be coated or treated with a material intend to promotebone growth or bone adhesion or an antimicrobial agent to preventinfections. For example, in some embodiments, the surface of the webstructure 22 may be coated with a biologic or a bone growth factor. Forexample, the biologic or growth factor may be physically secured to theweb structure 22 in a central portion of the implant 20 provided thereis the physical attachment of the biologic or growth factor. Thebiologic may include a coating, such as hydroxyapatite, bone morphaginicprotein (BMP), insulin-like growth factors I and II, transforming growthfactor-beta, acidic and basic fibroblast growth factor, platelet-derivedgrowth factor, or similar bone growth stimulant that facilitates goodbiological fixation between the bone growth and a surface of the implant20. The bone growth factor may include a naturally occurring substancecapable of stimulating cellular growth, proliferation and cellulardifferentiation (e.g., a protein or steroid hormone).

As shown in the FIGS. 1 and 2, the center portion of the spherical webstructure 22 defines a cylindrical passage 30. The central passage 30 isconfigured to receive an intramedullary nail extending therethrough(FIG. 3).

In the embodiment of the implant 44 shown in FIG. 9, the planar oraspherical portion of the implant 44 accommodates a plate 42 or the liketo facilitate attaching the combined porous web structure 45 and theplate 42 to bone using screws 48. For example, where an implant isimplanted adjacent to a bony structure, one or more structures may bedisposed on or extend from a surface (e.g., an interface plate) of theimplant that is intended to contact, and at least partially adhere to,the bony structure during use.

A method is provided that includes the steps of providing an opening ina foot or ankle 34 of a human, and installing into the opening theimplant 20, 44, 50, 54. The implant location is first prepared,including surgical dissection for forming an opening proximate the footor ankle 34 to the level of proposed implantation. Next, a bone bed canbe prepared from the adjacent bony structure either by using a sphericalreaming device or using a saw and osteotomes. The bone bed may be formedin either a joint or within a single bone. Bone graft material may bepacked in the bone bed or within the porous web structure 22 of theimplant 20. The implant 20 is then inserted into the bone bed. Theimplant 20 may be incorporated into the end surfaces established betweenan upper tibia bone 36 and an opposite calcaneous bone 38 and a talusbone 35. The shape of at least a portion of the implant 20 allows thebone or the joint surface on any side of the implant 20 to be placed ina preferred position, for example, to correct a deformity. FIGS. 6A-6Eshow the implant 20 disposed in respective openings of the foot andankle bones, including the tibia 36, the talus 35 and the calcaneous 38.

In some embodiments, inserting the implant 20 includes positioning theimplant 20 adjacent the boney structure, aligning the web structure 22with a complementary portion of the boney structure, or advancing acontact surface toward the boney structure such that at least the webstructure 22 is in contact or near contact with the boney structure. Insome embodiments, the implant 20 may be advanced until the contactsurface is in contact or near contact with the boney structure, suchthat at least portion or substantially all of the web structure 22 isdisposed in the boney structure.

The implant 20 then may, or may not be, fixed in place. In oneembodiment, an intramedullary nail 32 is inserted into the heel andthrough the passage 30 in the web structure 22 of the implant 20. Thenail 32 is driven into the end of the tibia 36 for fusing the foot andankle joint 34 (FIGS. 7A-7E). In an embodiment shown in FIG. 8, a tab 40integral with the web structure 22 may be included on the implant 20.The tab 40 may be secured to adjacent bone with staples, screws, plates,or other means of fixation. FIG. 11 shows openings in the intramedullarynail 32 for receiving at least one screw passing through another part ofthe foot and ankle joint.

FIGS. 13 and 14 schematically show the implants 44, 54 having anaspherical side and an egg-shape implant contacting adjacent bonystructure 56. As depicted, the implants 44, 54 are intended to bedisposed between the adjacent bony structures interfacing with bonestructure of a foot and ankle joint. The top of the implants 44, 54 maycouple to a portion of the first bony structure 56 disposed above theimplants and the bottom contact faces 28 may couple to the second bonystructure disposed below implants 44, 54.

Once the implant is positioned in the foot and ankle joint 34, theaccess point to the implant site may be closed using sutures or otherclosure devices.

Although the bone implant has been shown and described in considerabledetail with respect to only a few exemplary embodiments thereof, itshould be understood by those skilled in the art that I do not intend tolimit the invention to the embodiments since various modifications,omissions and additions may be made to the disclosed embodiments withoutmaterially departing from the novel teachings and advantages,particularly in light of the foregoing teachings. Accordingly, I intendto cover all such modifications, omission, additions and equivalents asmay be included within the spirit and scope of the bone implant asdefined by the following claims. In the claims, means-plus-functionclauses are intended to cover the structures described herein asperforming the recited function and not only structural equivalents butalso equivalent structures. Thus, although a nail and a screw may not bestructural equivalents in that a nail employs a cylindrical surface tosecure wooden parts together, whereas a screw employs a helical surface,in the environment of fastening wooden parts, a nail and a screw may beequivalent structures.

I claim:
 1. A method of securing an ankle joint, the method comprisingthe steps of: reconditioning end surfaces on a distal end of a tibiabone, a talus bone, and a calcaneous bone of the ankle joint, whereineach of the bone surfaces is reconditioned to have a concave surface;positioning a spherical component in a complementary manner against thereconditioned distal end surface of the tibia, the reconditioned surfaceof the talus and the reconditioned surface of the calcaneous, whereinthe component is configured to be placed in a bone bed at leastpartially formed from the reconditioned bone surfaces such that thecomponent is in contact with each of the reconditioned bone surfaces,the component defining an opening therethrough; selectively positioningthe ankle joint relative to the component for aligning an intramedullarynail with the distal end surface of the tibia; and driving anintramedullary nail configured to pass through the opening in thecomponent through the calcaneous and the opening in the component andinto the tibia.
 2. A method of securing an ankle joint, the methodcomprising the steps of: reconditioning end surfaces on a distal end ofa tibia bone, a talus bone, and a calcaneous bone of the ankle joint,wherein each of the bone surfaces is reconditioned to have a concavesurface; positioning a component having at least one convex surface in acomplementary manner against the reconditioned distal end surface of thetibia, the reconditioned surface of the talus and the reconditionedsurface of the calcaneous, wherein the component is configured to beplaced in a bone bed at least partially formed from the reconditionedbone surfaces such that the component is in contact with each of thereconditioned bone surfaces, the component defining an openingtherethrough; selectively positioning the ankle joint relative to thecomponent for aligning an intramedullary nail with the distal endsurface of the tibia; and driving an intramedullary nail configured topass through the opening in the component through the calcaneous and theopening in the component and into the tibia.
 3. The method as recited inclaim 1, wherein the component comprises a tab extending from thecomponent, and further comprising the step of fastening the tab to thetibia or the talus for further securing the component between the endsurfaces.
 4. The method as recited in claim 1, wherein theintramedullary nail defines a plurality of longitudinally spacedopenings, and further comprising the step of passing a fastener throughthe talus or the tibia and through at least one opening in the nail forfurther securing the component.
 5. The method as recited in claim 2,wherein the component comprises a tab extending from the component, andfurther comprising the step of fastening the tab to the tibia or thetalus for further securing the component between the end surfaces. 6.The method as recited in claim 2, wherein the intramedullary naildefines a plurality of longitudinally spaced openings, and furthercomprising the step of passing a fastener through the talus or the tibiaand through at least one opening in the nail for further securing thecomponent.